strings.js

/**
 * Find and replace in the provided string, but preserving case
 * If the new word is longer than the replaced one, ignore tail characters
 * @param {string} needle
 * @param {string} haystack
 * @param {string} newWord
 * @return {string} the resulting string, with all needle words transformed to newWord
 */
export function findAndReplacePreservingCase(needle, haystack, newWord) {
  // Write your code here

  if (typeof newWord !== 'string' || typeof needle !== 'string') {
    throw new Error('Not a string ')
  }

  return haystack.replaceAll(new RegExp(needle, 'gi'), (match) => {
    let resultat = ''

    for (let i = 0; i < match.length; i++) {
      const word = newWord[i] || ''
      if (match[i] === match[i].toUpperCase()) {
        resultat += word.toUpperCase()
      } else {
        resultat += word.toLowerCase()
      }
    }
    return resultat
  })
}